<!DOCTYPE HTML>
<html>

<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <title>string对象</title>
  <script type="text/javascript">
    var mystr = "Hello World!"
    document.write(mystr.substring(6) + "<br />");
    document.write(mystr.substring(0, 5));
  </script>
</head>

<body>
</body>

</html>